144 



MANUAL OF THE MOLLTJSCA. 



the smaller 



Shell pyramidal, with nearly a flat base ; whirls numerous, flat, variously 

 striated ; aperture oblique, rhombic, pearly inside ; columella 

 twisted, slightly truncated ; outer lip thin ; operculum horny, 

 multi-spiral. Fig. 88 (T. pica). 



Animal with 2 small or obsolete head-lobes between the 

 tentacles ; neck lappets large : sides ornamented with lobes, 

 and 3 5 cirri ; gill very long, linear ; lingual teeth 11, den_ 

 ticulated ; uncini 90, diminishing outwards. 



Distr., 150 sp. World-wide. Low- water to 15 fathoms ; 

 species range nearly to 100 fathoms. 



Fossil, 360 sp. Devonian . Europe, N. America, Chile. 



Sub-genera. Pyramis, Chemn., Tr. obeliscus, PI. X., fig. 6, columella 

 contorted, forming a slight canal. 



Gibbula, Leach. Tr. magus, Brit. Shell depressed, widely umbilicated ; 

 whirls tumid. Head-lobes largely developed; lateral cirri 3. 



Margarita, Leach. Tr. helicinus. PL X., fig. 7. Shell thin ; cirri 5 on 

 each side. Distr., 17 sp. Greenland, Brit., Falkland Islands. Near low- 

 water, under stones and sea- weed. 



Elenchus, Humph. (= Canthiridus, Montf.) E. iris. PI. X., fig. 8. 

 Smooth, thin, imperforate, with a prominent base. Australia, N. Zealand. 

 F. iris scarcely differs in form from Tr. zizyphinus ; E. ladius is like a 

 pearly phasianella ; and E. varians (bankivia, Menke) w r ould be called a 

 chemnitzia, if fossilized. PL X., fig. 9. 



ROTELLA, Lamarck. 



Etym., diminutive of rota, a wheel, (Syn., Helicina, Gray !) 

 Type, R. vestiaria. PL X., fig. 10. 



Shell, lenticular, polished ; spire depressed ; base callous ; lingual teeth 

 ; uncini numerous, sub-equal. 



13 



Distr., 10 sp. 



, fig. 12. 



India, Philippines, China, New Zealand. 

 MONODONTA, Lam. 



Etym., monos, one, and odous, (odontos) a tooth. 



Syn., labio, Oken. Clanculus, Montf. Otavia, Risso. 



Types, M. labeo. PL X., fig. 11. M. pharaonis. PL X., 



Shell, turbinated, few- whirled ; whirls spirally grooved and granulated : 

 lip thickened internally, and grooved ; columella toothed, more or less pro- 

 minently and irregularly ; operc. horny, many- whirled. 



Distr., 10 sp ? W. Africa, Red Sea, India, Australia. 



Fossil, (included with trochus) Devonian . Eifel. 



DELPHINULA (Roissy), Lam. 

 Etym., diminutive of delphinus, a dolphin. (= Cyclostoma, Gray !) 



